1. Field of the Invention
The present invention relates to a magnetic switch and, more particularly, to a circular magnetic switch that is provided with at least an anti-interference magnets between two magnets to avoid the interference generated from other magnets toward the magnetic induction element, and is suitable for portable lighting devices such as flashlights.
2. Description of the Prior Art
With respect to multifunctional portable lighting devices such as a flashlight, it is difficult to design the lighting devices where all setting and operations can be controlled by one key because of size, appearance, and waterproofing problems. Even though the design of multiple keys is applied, it is necessary to add many extra waterproof structures. Besides, some lighting devices are designed to have multiple keys controlled by pressing the keys at intervals and in sequence to perform different functions. It is difficult for users to definitely ascertain the instant status and to enter the desired mode directly.
It is widely known in the field of multifunctional portable lighting devices to produce electric current that are equivalent to different functional keys by using both of magnetic induction elements and magnets. Conventionally, the magnetic induction elements are welded on a round circuit board whereon is fixed in a tube made of plastics, metal, or other waterproof material. The magnets corresponding to the magnetic induction elements are fixed on an internal rotating ring of a ring structure outside the tube. The ring structure can also be made of plastics, metal, or other waterproof material. When the magnets are moved by turning the ring structure, the relatively positional changes of the magnets can be sensed by the magnetic induction elements for performing following corresponding procedures.
By reason of the ring structure can be turned 360 degrees, the magnets can be rotated and positioned in a step-type way by an elastic piece. Therefore, through the movement of the magnets, different combination patterns of the magnetic induction elements can be produced and the produced combination patterns can be detected by the scanning of buttons that are equivalent to quick buttons functionally. Besides, by providing the ring structure with different images, users can operate desired functions and ascertain the function used currently in order to overcome the drawbacks mentioned above. However, in practice, the magnetic induction element needs to be disposed corresponding to the magnet and consequently magnetic hysteresis may be produced. The magnetic hysteresis caused by other magnets will result in the interference of the normal function of the magnetic induction element. In other words, the magnetic induction element that should not be actuated is actuated as a result of the magnetic hysteresis. This phenomenon is obvious in small portable lighting devices with many combination patterns. Therefore, how to apply a magnetic switch to a small portable lighting device with many combination patterns is a crucial problem needs to be solved for people in the art.